Let \[f(x) =
\begin{cases}
3x + 5 &\text{if }x<-3, \\
7-4x&\text{if }x\ge -3.
\end{cases}
\]Find $f(5)$.
Solution: Because $5\ge -3$, we use the second case to determine that $f(5) = 7-4(5) = \boxed{-13}$.